ASSESSMENT OF PROPRIOCEPTIVE ALLODYNIA AFTER TOOTH CLENCHING

Eccentric muscle exercise can induce delayed onset muscle soreness (DOMS). It is known that vibratory stimulus is an effective method to stimulate mechanoreceptors and that 80-Hz vibratory stimulus increases pain in an eccentric exercised muscle (Weerakkody et al. 2001). Lund (1994) suggested that bruxism is related to DOMS. This study evaluates the effects of experimental tooth clenching on vibrotactile and pressure sensitivity in healthy females. Methods: Sixteen healthy females (mean age 32 ± 10) participated in this study, which comprised three sessions. In each session participants were randomly assigned to a tooth clenching exercise, with a clenching level of 10%, 20%, or 40% of maximal voluntary clenching (MVC). The first day of each session, patients did six bouts of tooth clenching exercises, each bout lasting 5 minutes during 1 hour. Registrations were made at baseline, after each bout of tooth clenching (short perspective), and after 24 and 48 hours. A Vibrameter®was used to measure the vibration threshold (VT). A fixed vibratory stimulus (100 Hz, 399.99-μm amplitude) was applied for 15 s and the perceived intensity of vibration (PIV) and perceived discomfort (PD) were rated on 0-50-100 scales (0 = no sensation; 50 = pain threshold/discomfort; 100 = worst imaginable pain/worst imaginable discomfort). An electronic algometer was used to measure pressure pain thresholds (PPT). A 0-10 visual analogue scale (VAS) measured pain intensity (VP) and fatigue (VF). All registrations were made on the central and most prominent part of the right masseter muscle. Results: No main effects of contraction level was observed for VT (P=0.184) or PIV (P=0.628), but there were significant time effects (P<0.001; P<0.05) with significant increases in VT at 30, 40, 50 and 60 min (Dunnett: P<0.05) and significant increase in PIV at 40 min compared to baseline (Dunnett: P<0.05). There were no main effects of contraction level (P=0.524) or time (P=0.705) for PD. For PPT there was no effect of contraction (P=0.819) but a significant time effect (P<0.01) with decreases at 50 and 60 min compared to baseline (Dunnett: P<0.05). Main effects of contraction level and time were observed for VP and VF (both P